This study will investigate the effect of the PCSK9 inhibitor alirocumab in patients with acute myocardial infarction undergoing percutaneous coronary intervention (PCI) in the infarct-related artery and receiving guideline-recommended high-intensity statin therapy. A serial, multivessel, intravascular ultrasound, near-infrared spectroscopy and optical coherence tomography imaging study will be performed to determine the change in plaque volume at week 52. A total of 220 patients will be enrolled in the study and randomized in a 1:1 ratio to either alirocumab or placebo.